The E.N. WOODS lease of the North Cowden Field is located in Ector County (West Texas) and produces from the Grayburg formation. The field is currently operated by TRIAD ENERGY CORPORATION of Houston, Texas. In 1983, TRIAD unitized the field for waterflooding operation. Oil production reached a peak of 381,480 BBU year in 1986 from 96,835 BBU year in 1983. The reservoir maintained a steady production rate over a period of 10 years since waterflood began with an average of 250,000 BBU year. The Oil rate has been in decline since 1994. As of December 1996, the unit produces approximately 100,000 barrels of oil per year. The task of this work was to evaluate the past performance of the E.N. WOODS Unit and to forecast its future economic performance by taking into consideration the geology, petrophysics and the production history of the reservoir. The Decline Curve Analysis feature of the Appraisal of Petroleum Properties including Taxation Systems (EDAPT) software along with the Production Management Systems (PMS) software were used to evaluate the original volume of hydrocarbon in place and estimate the reserve. The Black Oil Simulator (BOAST II) was then used to model the waterflooding operation and estimate the incremental oil production attributable to the water injection. BOAST II was also used to predict future performance of the reservoir. Waterflood study was conducted on the E.N. WOODS lease. A 3-D layered model was designed by taking into consideration the geology, petrophysics and production history of the unit. A decline curve analysis was performed based on the production data of the field. The original oil in place was estimated to be 31.4 million barrels and the reserve estimate as of January 1997 was 27.5 million barrels of oil. BOAST II was used to replicate past performance of the reservoir from 1970 to 1996. The model generated 3.86 million barrels of oil which was the exact amount of oil actually produced. The model also generated an average reservoir pressure of 1587 psi which was close to the actual 1500 psi.